1. Field of the Invention
The present invention is directed to a therapy apparatus of the type having a source having an acoustic axis, which generates acoustic waves converging in a focus lying on the acoustic axis.
2. Description of the Prior Art
A therapy apparatus of the above type is utilized for disintegrating calculi in the body of a patient, for treating body tissue, for example tumor tissue, as well as in pain therapy and in osteo restoration.
In the utilization of such a therapy apparatus, there is the problem of aligning the source over the body surface of a patient such that the acoustic axis of the source proceeds substantially through the treatment area in the body of the patient.
The problem of aligning the source over the body surface of a patient is addressed in German PS 195 43 344 by providing the source with a guide tube at whose exterior end a light source is secured, with optics arranged at the other end inside the source. The guide tube is introduced into the source that a light beam from the light source illuminates the body surface of the patient and is supplied by the optics to a display arrangement via an optical conductor arranged in the guide tube. In this way, the source can be optically aligned, for example relative to a marking applied on the body surface of the patient, and under which the treatment area is located.
German PS 196 15 342 discloses a therapy apparatus of the type initially described wherein the source of the therapy apparatus has a light-transparent region through which the acoustic axis of the source proceeds. Optical means including a light source are arranged in the light-transparent region of the source for acquiring image information from the body surface of a patient to be treated. In this way the source can be optically aligned, for example relative to a previously marked region on the body surface of a patient under which the treatment area is located.
Both possibilities of optical alignment of the source over the body surface of a patient, however, have the disadvantage that the actual position of the acoustic axis on which the focus of the source to be aligned onto the treatment area is only approximately known to the person who aligns the source. Further measures are therefore required in order to align the acoustic axis of the source such that it proceeds through the treatment area of the patient and in order to displace the focus of the source on the treatment area.
An object of the present invention is to provide a source of the type initially described wherein the alignment of the acoustic axis of the source onto a treatment area lying in the interior of the body of a patient is simplified.
This object is inventively achieved in a therapy apparatus having a source with an acoustic axis, wherein the source has a light generator that emits a focused light beam of visible light having a substantially parallel (i.e. non-diverging) beam path that substantially coincides with the acoustic axis of the source and makes his axis visible. Because the focused beam of the light generator coincides with the acoustic axis and makes it visible, the position and the orientation of the acoustic axis of the source can always be recognized, for example for a physician treating the patient with the therapy apparatus. The focused light beam casts a light spot on the body surface of the patient to be treated, which can be brought into coincidence in a simple way by appropriate alignment of the source with, for example, a marking applied on the body surface of the patient that identifies the treatment area. Since the acoustic axis is visible as a result of the light beam, the orientation of the acoustic axis relative to the treatment area can always be monitored, and the source can be correspondingly aligned relative to the treatment area such that the acoustic axis in fact proceeds through the treatment area rather than only grazing it. Because the focused light beam of the light generator coincides with the acoustic axis and makes it visible, the position and the orientation of the acoustic axis of the source can always be recognized, for example for a physician treating the patient with the therapy apparatus. The focused light beam casts a light spot on the body surface of the patient to be treated, which can be brought into coincidence in a simple way by appropriate alignment of the source with, for example, a marking applied on the body surface of the patient that identifies the treatment area. Since the acoustic axis is visible as a result of the light beam, the orientation of the acoustic axis relative to the treatment area can always be monitored, an d the source can be correspondingly aligned relative to the treatment area such that the acoustic axis in fact proceeds through the treatment area rather than only.
In one embodiment of the invention the source has a light-transparent region through which the acoustic axis of the source proceeds and in which light generator is arranged. In this way, the focused light beam of the light generator can be brought into coincidence with the acoustic axis in an especially simple way so that it can be made visible.
In another version of the invention, the light generator is removable from the light-transparent region of the source. This provides the possibility of introducing other components as needed, for example a locator in the form of an ultrasound unit, into the light-transparent region of the source in order to exactly align the focus of the source onto the treatment area in the body of a patient, or in order to be able to determine or observe the course of the treatment during therapy.
In a further embodiment of the invention the light generator has optics arranged in the beam path of the focused light beam that influence the focused light beam such that configured light that provides information about the position of the focus relative to the surface can be generated on a surface onto which the focused light beam is directed. In this way, not only the position and orientation of the acoustic axis relative to a treatment area of a patient can be seen, but also the position of the focus along the acoustic axis relative to the body surface of the patient can be displayed, at least approximately. When, for example, the depth position of a treatment area in the inside of the body of a patient is known on the basis of examinations that have been implemented, for example palpation, not only can the acoustic axis be aligned as to position and orientation without additional auxiliaries, but also the focus can be aligned onto the treatment area in the interior of the body of the patient on the basis of the information derivable from the configured light imaged on the body surface.
In a version this embodiment the configured light forms rings generated with the optics, with each ring of the configured light providing information about the position of the focus relative to the surface. The rings can be projected in different image planes that the focused light beam penetrates substantially at a right angle, with at least one ring of the configured light being imaged optically sharp in an image plane. When, for example, the spacing of the source of acoustic waves changes relative to the body surface of a patient, rings, preferably having different diameters, are imaged on the body surface, with at least one ring being imaged optically sharp on the body surface dependent on the image plane in which the body surface lies. Depth information about the position of the focus in the body thus can be obtained on the basis of the sharpness of the imaging of a ring and on the basis of the diameter of the ring. Rings with larger diameter are preferably imaged optically sharp on the body surface the as the source comes closer to the body surface. In this way, the respective ring that is imaged optically sharp can still be recognized, given a source arranged comparatively close to the body surface but not covered by the source.
In a further embodiment of the invention, the source, in addition to the aforementioned light generator, has a second light generator that emits a focused light beam of visible light with a substantially parallel beam path, with the focused light beam from the second light generator intersects the focused light beam of the first means for generating light in the focus of the source. In this way, depth information as to the position of the focus in the body of a patient can be acquired. When the focus of the source lies below the body surface of a patient, then a first light point or spot on the body surface is produced by the first light generator, which identifies the position of the acoustic axis. A second light point or spot is projected on the body surface by the second light generator. Dependent on the angle that the two focused light beams describe, the distance of the light points from one another is an indication of the distance of the focus of the source from the body surface. When, for example, the two focused light beams describe an angle of approximately 45xc2x0, then the distance of the first light point on the body surface from the second light point on the body surface approximately corresponds to the distance of the focus of the source from the body surface. When the acoustic axis resides at a right angle relative to the body surface and when the two light points lie in the plane of the body surface, the distance indication is relatively exact.
In a preferred embodiment of the invention the first and/or the second light generator is/are a laser, that is especially suited for generating a focused light beam having a substantially coherent beam path.